High temperature cast aluminum-copper-manganese-zirconium alloys with low temperature ductility

ABSTRACT

Disclosed herein are embodiments of an Al—Cu—Mn—Zr alloy for use with casting processes. The disclosed alloy embodiments provide fabricated objects, such as cast engine components comprising a heterogeneous microstructure and having good castability, resistance to hot tearing, and high ductility at room temperature. Methods for making and using alloy embodiments also are disclosed herein.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the earlier filing date of U.S.Provisional Patent Application No. 62/984,803, filed on Mar. 4, 2020,which is incorporated herein by reference in its entirety.

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

This invention was made with government support under Contract No.DE-AC05-000R22725 awarded by the U.S. Department of Energy. Thegovernment has certain rights in the invention.

FIELD

The present application is directed to embodiments of a castaluminum-copper-manganese-zirconium-based alloy and casting methodembodiments using the same to provide cast parts having favorablecasting properties and high ductility at room temperature for use invarious industrial applications.

BACKGROUND

High-temperature cast aluminum alloys are a key material in the designof high power density automobile engines. Traditional alloys comprisingaluminum, copper, manganese, and zirconium may offer an attractivematerial in this application, due to their strength at high temperature,favorable casting behavior, resistance to hot tearing, and goodmachinability; however, for such alloys, there is a trade-off betweencastability and ductility at low temperatures, placing practical limitson both the life cycle of the components made from such alloys and onthe size and shape of the parts that can be cast. There exists,therefore, a need in the art for improvedaluminum-copper-manganese-zirconium-based (or “ACMZ”) alloy embodimentsthat possess both good castability and room temperature ductility.

SUMMARY

Disclosed herein are alloy composition embodiments for castaluminum-copper-manganese-zirconium alloys. In one embodiment, the alloycomprises copper in an amount ranging from 7 wt % to 10 wt %, zirconiumin an amount ranging from greater than 0.3 wt % to 0.5 wt %, manganesein an amount ranging from 0.05 wt % to 1 wt %, silicon in an amountranging from greater than 0 wt % to 0.1 wt %, and a balance of aluminum.

Also disclosed herein are embodiments of a method comprising combiningcopper in an amount ranging from 7 wt % to 10 wt %, zirconium in anamount ranging from greater than 0.3 wt % to 0.5 wt %, manganese in anamount ranging from greater than 0.05 wt % to 1 wt %, silicon in anamount ranging from greater than 0 wt % to 0.1 wt %, and a balance ofaluminum to form a composition, melting the composition, and solidifyingthe composition to form an alloy.

The foregoing and other objects and features of the present disclosurewill become more apparent from the following detailed description, whichproceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are scanning electron microscope (SEM) micrographs showingthe microstructure of cast ACMZ alloys comprising 6.6 wt % copper with0.13 wt % Zr (FIG. 1A), and comprising 8 wt % copper with 0.23 wt % Zr(FIG. 1B); as seen in FIG. 1A, the ACMZ alloy with 6.6 wt % copperexhibits a granular aluminum matrix structure with isolatedintermetallic particles dispersed along the grain boundaries, and as canbe seen by FIG. 1B, the ACMZ alloy with 8 wt % copper exhibits agranular aluminum matrix structure with an interconnected layer of anintermetallic phase separating the grains.

FIG. 2 is a bar graph showing the chemical analysis, via atomic probe,of the intermetallic phase and matrix phase of two ACMZ alloys.

FIGS. 3A-3B are backscatter electron micrographs of an ACMZ alloycomprising 7.5 wt % copper, 0.45 wt % manganese, 0.23 wt % zirconium,0.05 wt % silicon, and a balance of aluminum, wherein FIG. 3A shows adistribution of intermetallic phases along the grain boundaries of thealloy matrix phase and FIG. 3B more clearly shows the boundaries betweenthe matrix phase grains, with the intermetallic phases distributedthereon.

FIGS. 4A-4B are micrographs of an ACMZ alloy comprising 7.5 wt % copper,0.14 wt % manganese, 0.35 wt % zirconium, 0.04 wt % silicon, ironimpurities of less than 0.1 wt %, and a balance of aluminum, whereinFIG. 4A shows a low magnification view of a microstructure having aroughly uniform distribution of equiaxed grains; and FIG. 4B shows adistribution of intermetallic phases along the grain boundaries of thealloy matrix phase and within the bulk volume of the matrix phasegrains.

FIG. 5 is a scatter plot of tensile data for ACMZ alloys havingzirconium content ranging from 0 wt % to 0.35 wt % and copper contentranging from 7.3 wt % to 8.0 wt % and which shows that increasingductility values are observed with increasing zirconium content.

FIG. 6 is a scatter plot of tensile data for ACMZ alloys having anominal composition of Al-7.5Cu-xZr-0.15Mn-0.05Si, where the numbersindicate wt % of each element, and x indicates the wt % zirconium andwherein x ranges from 0 to 0.4; the tensile data demonstrate increasingductility values with increasing zirconium content.

DETAILED DESCRIPTION I. Overview of Terms

The following explanations of terms are provided to better describe thepresent disclosure and to guide those of ordinary skill in the art inthe practice of the present disclosure. As used herein, “comprising”means “including” and the singular forms “a” or “an” or “the” includeplural references unless the context clearly dictates otherwise. Theterm “or” refers to a single element of stated alternative elements or acombination of two or more elements, unless the context clearlyindicates otherwise.

Unless explained otherwise, all technical and scientific terms usedherein have the same meaning as commonly understood to one of ordinaryskill in the art to which this disclosure belongs. Although methods andcompounds similar or equivalent to those described herein can be used inthe practice or testing of the present disclosure, suitable methods andcompounds are described below. The compounds, methods, and examples areillustrative only and not intended to be limiting, unless otherwiseindicated. Other features of the disclosure are apparent from thefollowing detailed description and the claims.

Unless otherwise indicated, all numbers expressing quantities ofcomponents, molecular weights, percentages, temperatures, times, and soforth, as used in the specification or claims are to be understood asbeing modified by the term “about.” Accordingly, unless otherwiseindicated, implicitly or explicitly, the numerical parameters set forthare approximations that can depend on the desired properties soughtand/or limits of detection under standard test conditions/methods. Whendirectly and explicitly distinguishing embodiments from discussed priorart, the embodiment numbers are not approximates unless the word “about”is recited. Furthermore, not all alternatives recited herein areequivalents.

The following terms and definitions are provided:

Alloy: A metal made by melting and mixing two or more different metals.For example, an aluminum alloy is a metal made by combining aluminum andat least one other metal. In some instances, an alloy is a solidsolution of metal elements.

Bulk Ductility: This term refers to the ductility of the alloy bulkportion of a cast component other than a hardened surface portion of thecast component.

Cast Alloy: An alloy that is casted and is not additively manufactured.

Consists Essentially Of: The phrase “consists essentially of” means thatthe alloys do not comprise, or are free of, additional components thataffect one or more physical characteristics (i.e., change a numericalvalue of the physical characteristic by more than 5% relative to thevalue in the absence of the impurity or component), such as themicrostructural stability and/or strength of the alloy composition orcomponents formed from the alloy composition by additive manufacturing.Such embodiments consisting essentially of the above-mentionedcomponents can, however, include impurities and other components that donot materially affect the physical characteristics of the alloycomposition; however, those impurities and other components that domarkedly alter the physical characteristics, such as the microstructuralstability, strength, and/or other properties that affect performance athigh temperatures, are excluded.

Ductility: This term refers to a solid material's ability to deformunder tensile stress, often characterized by the material's ability tobe stretched into a wire. In some embodiments, ductility may bequantified by the percent elongation in a tensile test, defined as themaximum elongation of the gage length divided by the original gagelength:

${{percent}\mspace{14mu}{elongation}} = {\frac{{{final}\mspace{14mu}{gage}\mspace{14mu}{length}} - {{initial}\mspace{14mu}{gage}\mspace{14mu}{length}}}{{initial}\mspace{14mu}{gage}\mspace{14mu}{length}} \times 100}$

The test is performed by providing a test piece of the solid material,such as a rod, marking an initial gage length, applying a tensile forceto elongate the test piece until it fractures through a “neck,” and thenfitting the broken parts together and measuring the final gage length(i.e., the distance between the marks made initially). In additionalembodiments, ductility can be measured in terms of reduction of thecross-sectional area of the test piece at the plane of fracture, whereinthe minimum final cross-sectional area is measured after fracture:

${{percent}\mspace{14mu}{reduction}\mspace{14mu}{of}\mspace{14mu}{area}} = {\frac{{{area}\mspace{14mu}{of}\mspace{14mu}{original}\mspace{14mu}{cross}\mspace{14mu}{section}} - {{minimum}\mspace{14mu}{final}\mspace{14mu}{area}}}{{area}\mspace{14mu}{of}\mspace{14mu}{original}\mspace{14mu}{cross}\mspace{14mu}{section}} \times 100.}$

Grain Refiner: A chemical alloy additive which, when added to an alloy,results in a microstructure having a smaller average grain size than isexhibited in the absence of the grain refiner. Often, this isaccomplished by altering the rates of grain nucleation and/or graingrowth as the alloy is solidified.

Hot Tearing: A type of alloy casting defect that involves forming anirreversible failure (or crack) in the cast alloy as the cast alloycools. Hot tearing may produce cracks on the surface or inside the castalloy. Often a main tear and numerous smaller branching tears followingintergranular paths are present.

Intermetallic phase: A solid-state compound containing two or moremetallic elements and exhibiting metallic bonding, defined stoichiometryand/or ordered crystal structure, optionally with one or morenon-metallic elements. In some instances, an alloy may include regionsof a single metal and regions of an intermetallic phase. In a quaternaryalloy comprising aluminum, copper, manganese, and zirconium, theintermetallic phase may comprise both aluminum and copper, and in somecases may also comprise zirconium and/or manganese. Alloys havingadditional alloying elements may incorporate some portion of thoseelements in the intermetallic phase.

Microstructure: The fine structure of an alloy (e.g., grains, cells,dendrites, rods, laths, lamellae, precipitates) that can be visualizedand examined with a microscope at a magnification of at least 25×.Microstructure can also include nanostructure, i.e., structure that canbe visualized and examined with more powerful tools, such as electronmicroscopy, atomic force microscopy, X-ray computed tomography, etc.

TiBor: A master alloy grain refiner comprising aluminum, titanium, andboron. In a commonly-used TiBor composition, the alloy has a nominaltitanium content of 5 wt %, a nominal boron content of 1 wt %, and abalance of aluminum.

II. Introduction

Due to their light weight and favorable strength-to-weight ratios, castaluminum alloys are increasingly sought for high-performance structuralcomponents. Of particular importance to developing automotive engineshaving higher power densities is obtaining cast aluminum alloys havingimproved mechanical properties at elevated temperature. Aluminum alloycompositions utilizing aluminum, copper, manganese, and zirconium as themain alloying elements are particularly attractive for use in automotiveengines for this reason. These Al—Cu—Mn—Zr (“ACMZ”) alloys demonstratenoteworthy levels of strength at elevated temperature in addition togood castability, hot tear resistance, sand thermal conductivity, andare additionally relatively easy to machine.

The addition of copper to these ACMZ alloys has been found to furtherimprove their castability, reducing the tendency of the alloys to hottear during the casting process. Further additions of copper, forexample at concentrations above 7.3 wt % copper, may additionallyimprove resistance of the alloys to mechanical creep at hightemperatures, and can offer additional improvements to the thermalconductivity of the alloys. However, additional copper content alsocauses the formation of correspondingly greater quantities of a brittleAl—Cu intermetallic phase within the alloy. This phase accumulates atthe grain boundaries between matrix grains of the alloys, as shown inFIGS. 1A and 1B. At elevated concentrations, this phase causes thealloys to become more brittle, especially at lower temperatures.Furthermore, this Al—Cu intermetallic phase may accumulate in elongated,interconnected structures which serve as stress concentrators, greatlyinhibiting the ability of the alloy to plastically deform. Thelow-temperature ductility of an alloy can play a part in determining thelow-cycle fatigue resistance of the alloy. Low-cycle fatigue resistance,in turn, is a factor to be considered in engine design, since enginesand engine components are designed to account for the fatigue resistanceof the alloys from which they are manufactured. Furthermore, theroom-temperature ductility of high-copper ACMZ alloys can be low enoughto also reduce the tensile strength of these alloys at low temperature.

There exists, therefore, a demand for ACMZ alloy embodiments thatexhibit the s capable of both the favorable castability, hightemperature strength, and thermal conductivity of high-copper ACMZalloys and of retaining high ductility at lower temperatures. Withoutbeing limited to any particular theory, it is currently believed thatthe addition of increased zirconium content to ACMZ alloys may dispersethe Al—Cu intermetallic into particles with rounded geometries that havea smaller embrittling impact than the elongated, interconnectedstructures previously observed. As discussed in greater detail below,the present disclosure is directed to ACMZ alloy embodiments suitablefor the casting of parts with complex geometries having elevatedzirconium content and retaining high ductility at low temperatures orroom temperatures. The present disclosure is also directed to methods ofcasting ACMZ alloy embodiments having elevated zirconium content, and toembodiments of fabricated components of the same produced by thesecasting method embodiments.

III. Alloy Embodiments

Disclosed herein are aluminum alloy compositions. The disclosed aluminumalloy compositions can compose a multicomponent combination of aluminum,copper, manganese, and zirconium. The Al—Cu—Mn—Zr alloy embodiments arespecifically designed for favorable casting behavior, are resistant tohot tearing, have high at elevated temperatures, and retain highductility at lower temperatures. Such alloys may be suitable, forexample, for use in automobile engines, aerospace components, and thelike where components of complex geometries must be cast from alloysthat remain strong at high temperatures and which retain sufficientductility at all temperatures. In some embodiments, the Al—Cu—Mn—Zralloy can comprise Al, Cu, Mn, and Zr as the main alloying componentsand can further comprise other minor alloying elements and/or traceimpurities.

In particular disclosed embodiments, the alloy compositions disclosedherein are made using an alloy design approach that includesincorporating elevated copper content to improve castability and reducethe susceptibility of the alloy to hot tearing. Because additionalcopper content in aluminum alloys may cause the formation ofaluminum-copper intermetallic phases at the boundaries between thealuminum matrix grains of the alloy, some embodiments further includeelemental additives to disperse and “round” the aluminum-copperintermetallic phases of aluminum alloys having elevated copper content.A rounded and dispersed geometry may, in these embodiments, providelower stress concentrations near the aluminum-copper intermetallicphases, which in turn may contribute to improved alloy ductility at lowtemperatures. Without being limited to any particular theory, theaddition of certain alloying elements may also cause a fraction of thealuminum-copper intermetallic phases to move away from the grainboundaries to locations within the grain bulk, further reducing stressconcentration at the grain boundaries of the alloys disclosed herein.

Embodiments of the aluminum alloy compositions described herein cancomprise aluminum (Al), copper (Cu), manganese (Mn), zirconium (Zr),nickel (Ni), cobalt (Co), titanium (Ti), boron (B), iron (Fe), magnesium(Mg), antimony (Sb), and any combinations thereof. In particulardisclosed embodiments, the aluminum alloys consist essentially ofaluminum (Al), copper (Cu), manganese (Mn), zirconium (Zr), nickel (Ni),cobalt (Co), titanium (Ti), boron (B), iron (Fe), magnesium (Mg), andantimony (Sb). In such embodiments, “consist essentially of” means thatthe alloys do not comprise, or are free of, additional components thataffect one or more physical characteristics (i.e., change a numericalvalue of the physical characteristic by more than 5% relative to thevalue in the absence of the impurity or component), such as themicrostructural stability and/or strength of the cast alloy compositionor the hot tearing susceptibility obtained from this combination ofcomponents. Such embodiments consisting essentially of theabove-mentioned components can, however, include impurities and othercomponents that do not materially affect the physical characteristics ofthe alloy composition; however, those impurities and other componentsthat do markedly alter the physical characteristics, such as themicrostructural stability, strength, hot tearing, and/or otherproperties that affect performance at high temperatures, are excluded.In yet additional embodiments, the aluminum alloy compositions describedherein can consist of aluminum (Al), copper (Cu), manganese (Mn),zirconium (Zr), nickel (Ni), cobalt (Co), titanium (Ti), boron (B), iron(Fe), magnesium (Mg), and antimony (Sb).

ACMZ alloy embodiments disclosed herein can comprise Cu in an amountranging from 6 wt % to 13 wt %, such as 6 wt % (or higher) to 12 wt %, 6wt % (or higher) to 11 wt %, 6 wt % (or higher) to 10 wt %, 6 wt % (orhigher) to 9 wt %, or 6 wt % (or higher) to 8 wt %, wherein such amountsinclude nominal and/or measured amounts. In some embodiments, Cu can bepresent in an amount ranging from more than 7 wt % to 13 wt %, such as 7wt % to 12 wt %, or 7 wt % to 11 wt %, or 7 wt % to 10 wt %, or 7 wt %to 9 wt %, wherein such amounts include nominal and/or measured amounts.In particular embodiments, Cu can be present in an amount ranging from 7wt % to 10 wt %, such as 7 wt %, 8 wt %, 9 wt %, or 10 wt %, whereinsuch amounts include nominal and/or measured amounts. In onerepresentative embodiment, the amount of Cu can be 7.35 wt %, which canbe a nominal and/or measured amount.

ACMZ alloy embodiments disclosed herein can also comprise Mn rangingfrom greater than 0 wt % to 1 wt % Mn, such as greater than 0 wt % to 1wt %, greater than 0 wt % to 0.8 wt %, greater than 0 wt % to 0.6 wt %,greater than 0 wt % to 0.4 wt %, greater than 0 wt % to 0.2 wt %,wherein such amounts include nominal and/or measured amounts. In someembodiments, Mn can be present in an amount ranging from 0.05 wt % (orhigher) to 1 wt % Mn, such as 0.05 wt % (or higher) to 0.8 wt %, 0.05 wt% (or higher) to 0.6 wt %, 0.05 wt % (or higher) to 0.4 wt %, or 0.05 wt% (or higher) to 0.2 wt %, wherein such amounts include nominal and/ormeasured amounts. In other embodiments, Mn can be present in amountsranging from 0 wt % to 0.5 wt %, such as 0.1 wt %, 0.2 wt %, 0.3 wt %,0.4 wt %, or 0.5 wt %, wherein such amounts include nominal and/ormeasured amounts. In one representative embodiment, the amount of Mn canbe 0.14 wt %, which can be a nominal and/or measured amount.

In some embodiments of the ACMZ alloys described herein, Zr can bepresent in an amount ranging from 0.3 wt % to 0.5 wt %, such as 0.3 wt %(or higher) to less than 0.5 wt %, 0.3 wt % (or higher) to 0.45 wt %,0.3 wt % (or higher) to 0.4 wt %, 0.3 wt % (or higher) to 0.35 wt %, 0.3wt % (or higher) to 0.3 wt %, or 0.3 wt % (or higher) to 0.25 wt %,wherein such amounts include nominal and/or measured amounts. In otherembodiments, Zr can be present in amounts ranging from 0.3 wt % to lessthan 0.5 wt %, such as 0.3 wt %, 0.35 wt %, 0.4 wt %, 0.45 wt %, whereinsuch amounts include nominal and/or measured amounts. In onerepresentative embodiment, the amount of Zr can be 0.4 wt %, which canbe a nominal and/or measured amount. In particular embodiments, theamount of Zr is not greater than 0.45 wt %.

In some embodiments of the ACMZ alloys described in here, Si may bepresent in amounts ranging from greater than 0 wt % to 0.1 wt %, whereinsuch amounts include nominal and/or measured amounts. Without beinglimited to any particular theory, it is currently believed that thepresence of silicon in the ACMZ alloy embodiments disclosed herein canimprove the size range and distribution of precipitate phases in thesolidified alloy, and can enhance or preserve the thermal stability ofthe precipitate phases. In one representative embodiment, the amount ofSi can be 0.04 wt %, which can be a nominal and/or measured amount.

The amount of aluminum present in the above-mentioned alloys can make upthe balance of the alloy composition, after Cu, Mn, Zr, Si, and anyother minor elements or impurities have been accounted for.

Without being limited to any particular theory, in some embodiments, thezirconium content of the alloy may be incorporated in thealuminum-copper intermetallic phases, thereby modifying the interfacialfree energy between the aluminum matrix phase and the aluminum-copperintermetallic phase, causing the aluminum-copper intermetallic phases tohave a more rounded morphology. The substitutional inclusion ofzirconium may additionally serve to disperse the aluminum-copperintermetallic phase, for example, by causing a fraction of thealuminum-copper intermetallic phases to form within the bulk of thealuminum matrix grains, rather than at the boundaries of the aluminummatrix grains. In these embodiments, it is to be appreciated that thedispersion of a fraction of the aluminum-copper intermetallic phasesthrough the bulk volume of the aluminum matrix grains will reduce thefraction of the aluminum-copper intermetallic phase particles that aredistributed at the grain boundaries at any constant level of totalaluminum-copper intermetallic phase present in the ACMZ alloy. In someembodiments, the zirconium content in the ACMZ alloy may further cause a“rounding” of the aluminum-copper intermetallic phase particles, causingthem to take on a more spherical morphology. Without being limited toany single theory of operation, it is believed that such roundedaluminum-copper intermetallic phases, when compared to flat orplate-like intermetallic phases, may have a reduced effect as stressconcentrators, thereby improving the overall ductility of the alloy.

In some embodiments, minor alloying elements that can be present in theACMZ alloys disclosed herein include nickel, cobalt, titanium, boron,iron, magnesium, antimony, or any combination thereof. In someembodiments, the amount of boron can be up to 0.07 wt % boron, such as<0.067 wt % boron, <0.04 wt % boron, <0.033 wt % boron, or <0.02 wt %boron, wherein such amounts include nominal and/or measured amounts. Insome embodiments, the amount of titanium present in the compositions canrange from 0 wt % to 0.3 wt %, such as greater than 0 wt % to 0.3 wt %,or greater than 0 wt % to less than 0.3 wt %, or greater than 0 wt % toless than 0.2 wt %, or greater than 0 wt % to 0.15 wt %, or greater than0 wt % to 0.1 wt %, or greater than 0 wt % to 0.05 wt %, wherein suchamounts include nominal and/or measured amounts. The addition oftitanium and/or boron to the alloy composition may, in some embodiments,have a grain refining effect.

The aluminum alloy compositions disclosed herein can comprise additionalcomponents, such as grain refiners, which can include master alloys. Inparticular disclosed embodiments, the amount of grain refiner includedin the composition can be greater than, such as one order of magnitudegreater than, the amount of grain refiner used in conventionalcompositions. In some embodiments, the amount of grain refiner includedwith the compositions can be selected based on a target weight percentof titanium that is to be added to the composition by introduction ofthe grain refiner. In such embodiments, the desired amount of additionaltitanium that is to be added to the composition is identified and thenthe amount of the master alloy to be added to a specific metal volume ofthe ACMZ alloy to increase the titanium amount by the additional amountis calculated. In particular disclosed embodiments, the amount of thegrain refiner that is added can vary with the type of master alloy used.

As indicated above, the grain refiner can contribute to the amount oftitanium present in the alloy compositions. For example, using a grainrefiner can result in the composition comprising an additional amount oftitanium (relative to the amount of any titanium that may be included asa minor alloying element), such as from 0.02 wt % to 0.2 wt % additionalTi, or from 0.02 wt % to 0.15 wt % additional Ti, or from 0.02 wt % to0.1 wt % additional Ti. In particular disclosed embodiments, the amountof additional Ti introduced by adding a grain refiner can be 0.02 wt %,0.1 wt %, or 0.2 wt %. Suitable grain refiners include, but are notlimited to grain refiners that facilitate nucleation of new grains ofaluminum. Some grain refiners can include, but are not limited to, grainrefiners comprising aluminum, titanium, boron, and combinations thereof,which can include master alloys. In particular disclosed embodiments,the grain refiner can be a TiBor master alloy grain refiner, which is agrain refiner comprising a combination of aluminum, titanium, and boron.The grain refiner can comprise titanium in an amount ranging from 2 wt %to 6 wt %, such as 3 wt % to 6 wt %, or 3 wt % to 5 wt %; boron in anamount ranging from 0.5 wt % to 2 wt %, such as 0.5 wt % to 1 wt %, or0.75 wt % to 1 wt %; and aluminum making up the remainder wt %; and anycombination thereof. In exemplary embodiments, the TiBor grain refinercomprises 94 wt % aluminum, 5 wt % titanium, and 1 wt % boron, or 96 wt% aluminum, 3 wt % titanium, and 1 wt % boron. Other grain refiners canbe used, such as other TiB grain refiners, TiC grain refiners, amongothers.

In some embodiments of the ACMZ alloys disclosed herein, the alloy mayalso include nickel, cobalt, magnesium, antimony, or any combinationthereof. In some embodiments, the amount of any nickel or magnesium is,for each element individually less than 0.01 wt %, such as from 0 to0.01 wt %, wherein such amounts include nominal and/or measured amounts.In some embodiments, the amount of any cobalt or antimony, for eachelement individually, is less than 0.1 wt %, such as from 0 wt % to 0.1wt %, wherein such amounts include nominal and/or measured amounts. Insome embodiments, iron may be present as an impurity element, but it isto be understood that iron content is generally low enough to have nosubstantial impact on the physical and/or chemical properties of thealloys disclosed herein.

In one specific embodiment, the ACMZ alloy can comprise 7.5 wt % copper,0.4 wt % zirconium, 0.15 wt % manganese, less than 0.05 wt % silicon,trace or impurity amounts of iron, with the balance of the alloy made upby aluminum. Element amounts specified in this paragraph can be nominaland/or measured amounts.

In another specific embodiment, the ACMZ alloy can comprise 7.5 wt %copper, 0.1 wt % zirconium, 0.15 wt % manganese, less than 0.05 wt %silicon, trace or impurity amounts of iron, with the balance of thealloy made up by aluminum. Element amounts specified in this paragraphcan be nominal and/or measured amounts.

In another specific embodiment, the ACMZ alloy can comprise 7.5 wt %copper, 0.23 wt % zirconium, 0.45 wt % manganese, 0.05 wt % silicon, andtrace impurity elements with the balance of the alloy made up byaluminum. Element amounts specified in this paragraph can be nominaland/or measured amounts.

IV. Method Embodiments

Also disclosed herein are embodiments of casting methods suitable foruse with alloys according the compositions disclosed herein. The castingmethod embodiments described herein can involve bulk solidificationmethods suitable for metal alloys, such as, but not limited to, sandcasting, die casting, pressurized die casting, and investment casting.Casting the ACMZ alloy compositions disclosed herein can comprisecombining the desired amounts of the alloy (e.g., aluminum, copper,manganese, and zirconium, along with any minor alloying elements, suchas silicon, nickel, cobalt, and antimony), melting the selected elementsto form an ACMZ melt, optionally adding a grain refiner master alloy tothe ACMZ melt, casting the ACMZ melt, and optionally machining the ACMZcasting to the final desired geometry.

In particular embodiments, the ACMZ alloy embodiments disclosed hereincan be made according to the following method embodiments. In particulardisclosed embodiments, the aluminum alloy compositions described hereincan be made by combining cast aluminum alloy precursors with pre-meltedalloys that provide high melting point elements. The cast aluminum alloyprecursors are melted inside a reaction vessel (e.g., graphite crucibleor large-scale vessel). The pre-melted alloys are prepared byarc-melting in advance. The reaction vessel is retained inside a boxfurnace at, for example, 775° C., with Ar cover gas for a suitableperiod of time (e.g., 30 minutes or longer). The melted Al alloys arethen poured into a pre-heated steel mold (e.g., pre-heated at 300° C.).Prior to the pouring, the molten metal inside the crucible is stirred byusing a graphite rod pre-heated at 300° C., to verify that all elementsor pre-melted alloys were fully dissolved into the liquid. The methodsteps described above are scalable, and therefore are suitable forindustrial scale processes.

In some embodiments of the casting methods disclosed herein, the castingprocess may further include the addition of one or more grain refinersto the ACMZ melt. In certain embodiments, a preferred grain refiner maybe TiBor, however it is to be understood that other grain refinerssuitable for refining the microstructure of aluminum alloys may also beused. In such embodiments, it may be desirable to minimize the amount oftime between the addition of the grain refiner to the ACMZ alloy meltand the casting of the ACMZ alloy melt. Advantageously, the mixture canbe poured into a pre-heated mold substantially immediately (e.g., lessthan 10 minutes) after adding the grain refiner. For example, themixture may be poured into the pre-heated mold within 1-5 minutes ofadding the grain refiner, such as within 5 minutes, within 4 minutes,within 3 minutes, within 2 minutes, or within 1 minute of adding thegrain refiner.

V. Cast Object Embodiments

Also disclosed herein are various embodiments of fabricated objects thatcan be prepared from the above-mentioned alloy compositions, accordingto the above-mentioned methods of alloy preparation and casting.

The microstructure of fabricated components made from the ACMZ alloysand casting processes of the present disclosure can comprise analuminum-based matrix phase and one or more intermetallic phases. Insome embodiments disclosed herein, the intermetallic phase can be analuminum-copper intermetallic.

In some embodiments, the aluminum-based matrix phase is arranged in acellular, crystalline structure, with the aluminum-copper intermetallicphase disposed at least in part along the boundaries between crystallinealuminum-based matrix grains. In certain embodiments, thealuminum-copper intermetallic phase can be disposed at least in partwithin the bulk volume of the aluminum-based matrix phase grains. Inparticular embodiments, the aluminum-copper intermetallic phase can besimultaneously partially disposed along the boundaries betweenaluminum-based matrix phase grains and partially disposed within thebulk volume of the aluminum-based matrix phase grains.

The aluminum-based matrix phase, according to the various embodimentsdisclosed herein may comprise a composition in which aluminum is theprimary component, by weight percentage. In certain embodiments, thealuminum-based matrix phase may additionally comprise copper, manganese,zirconium, titanium, boron, silicon, nickel, cobalt, antimony, or anycombination thereof. In one specific embodiment, the matrix phase maycomprise aluminum, manganese, zirconium, and copper. It is to beappreciated that, at any nominal composition, the aluminum-based matrixphase may additionally comprise other elements, such as iron, atimpurity-level concentrations, such as less than 0.1 wt % iron.

The aluminum-copper intermetallic phase, according to some embodiments,may comprise copper, aluminum, and one or more additional elements. Insome embodiments, the aluminum-copper intermetallic phase may consist ofcopper and aluminum. In certain embodiments, the aluminum-copperintermetallic phase may further comprise additional alloying elementssuch as zirconium and manganese. Without being limited to any particularoperational theory, it is currently believed that, in certainembodiments, the inclusion of zirconium in the aluminum-copperintermetallic phase causes the aluminum-copper intermetallic phase toform with a generally rounded geometry. In embodiments havingaluminum-copper intermetallics with a generally rounded geometry, thealuminum-copper intermetallic particles may be spaced further apart thanwould be expected at lower levels of zirconium, having correspondinglyless interconnectivity between the aluminum-copper intermetallicparticles.

In embodiments of fabricated components prepared from compositionsincluding one or more grain refiners, the microstructure of thefabricated component may additionally include titanium boride particles(e.g. TiB₂) dispersed throughout the bulk volume of the ACMZ alloyfabricated component. Titanium boride is a ceramic material that remainschemically stable at high temperatures, and when dispersed in an alloymelt in the form of fine particles, may offer additional sites for thenucleation of metallic grains upon solidification. It currently isbelieved that the inclusion of grain refiners, such as TiBor, cause theformation of particles of titanium boride in the alloy while it ismolten. These titanium borides have crystallographic planes with alattice spacing similar to that of aluminum, thereby providinghighly-efficient nucleation sites for the formation of aluminum grainsupon the cooling of the fabricated component. In such embodiments,aluminum matrix grains may form more rapidly as the melt cools,providing for a greater total number of aluminum matrix grains, witheach individual grain having a correspondingly smaller volume.

In particular embodiments using TiBor as a grain refiner, zirconium maysubstitutionally replace titanium in the titanium boride particlesformed at elevated temperatures, forming titanium-zirconium boride. Thepresence of zirconium in the lattice of the titanium-zirconium borideparticles may, in some embodiments, distort the lattice parameter of theboride, causing a mismatch between the lattice spacing of thetitanium-zirconium boride and aluminum matrix, which in turn may reducethe efficiency of the titanium-zirconium boride as a grain refiner.

As illustrated in FIG. 5 and FIG. 6, objects cast using the alloycompositions and methods disclosed herein can exhibit high ductility andstrength at temperatures below 200° C., such as at room temperature. Asshown in FIG. 5, objects cast according to the alloy and methodembodiments disclosed herein may demonstrate increasing levels ofductility at room temperature with increasing zirconium content in thealloy. In particular, in alloys having zirconium content above 0.3 wt %,such as 0.35 wt %, 0.4 wt %, or 0.45 wt % demonstrate ductility levelsin excess of 2% total elongation, such as 3% total elongation, 4% totalelongation, 5% total elongation, 6% total elongation, or 7% totalelongation. In one specific embodiment, as shown in FIG. 6, objectsfabricated from ACMZ alloys according to alloy embodiments disclosedherein having more than 0.3 wt % zirconium content, such as 0.4 wt %zirconium content, display improved ductility when compared to alloyswith a similar nominal and/or measured compositions with less than 0.3wt % zirconium, such as 0.1 wt % zirconium.

Fabricated components according to the embodiments disclosed herein maybe cast in any suitable range of cast geometries. In certain embodimentshaving 7 wt % copper to 13 wt % copper, such as 7 wt % copper, 9 wt %copper, 11 wt % copper, or 13 wt % copper, the fabricated object mayexhibit a reduced propensity to hot tear or hot crack. In particular,components cast from ACMZ alloys according to the embodiments herein maydemonstrate a monotonic reduction of susceptibility to hot tearing asthe copper content of the alloy is increased, with some embodimentsincreased up to 13 wt % copper. Fabricated components having suchcompositions can be cast into increasingly complex geometries withoutthe resulting components exhibiting tearing or cracking as they cool. Itis to be appreciated that this offers fabricated components according tothe present disclosure certain advantages, such as a reduction in theamount of machining that is required to produce a finished componentthat meets final geometric tolerance requirements and an increased rangeof useful components that may be cast according to the embodimentsdisclosed herein, to name a few.

Fabricated ACMZ objects made using the embodiments disclosed hereinexhibit a combination of mechanical properties, thermal properties, andcasting behavior that cannot be obtained using traditional ACMZ castingalloys. In particular disclosed embodiments, the fabricated ACMZ alloyobjects are components used in the automotive, locomotive, aircraft, andaerospace industries. In some embodiments, the cast object is anautomotive engine cylinder. Other exemplary products include, but arenot limited to other automotive power train components (such as enginepistons, blocks water-cooled turbocharger manifolds, and otherautomotive components), aerospace components, heat exchanger components,and any other components requiring aluminum alloys that are suitable forcasting complex shapes, do not lose structural integrity and/or strengthat high temperatures (e.g. temperatures above 200° C., and retain highductility at reduced temperatures).

VI. Overview of Several Embodiments

Disclosed herein are embodiments of an alloy composition comprising: 7wt % to 10 wt % copper; greater than 0.3 wt % to 0.5 wt % zirconium;0.05 wt % to 1 wt % manganese; greater than 0 wt % to 0.1 wt % silicon;and aluminum.

In some embodiments the alloy is a cast alloy and has a microstructurecomprising an aluminum matrix phase and an intermetallic phasecomprising copper and aluminum.

In any or all of the above embodiments, the intermetallic phase has arounded geometry.

In any or all of the above embodiments, the intermetallic phase furthercomprises zirconium.

In any or all of the above embodiments, the aluminum matrix phasefurther comprises a plurality of grain boundaries between aluminummatrix grains and the intermetallic phase is partially distributed alongthe plurality of grain boundaries and partially distributed within thevolume of the aluminum matrix grains.

In any or all of the above embodiments, wherein the alloy furthercomprises one or more elements selected from nickel, cobalt, titanium,boron, iron, magnesium, or antimony.

In any or all of the above embodiments, the titanium is present in thealloy in an amount ranging from greater than 0.0 wt % to 0.3 wt % andthe boron is present in the alloy in an amount ranging from greater than0 wt % to less than 0.07 wt %.

In any or all of the above embodiments, the alloy comprises 7.5 wt %copper, greater than 0.3 to 0.4 wt % zirconium, 0.15 wt % Mn, less than0.05 wt % silicon, and a balance of aluminum.

In any or all of the above embodiments, the alloy comprises greater than0.3 wt % zirconium to less than 0.5 wt % zirconium.

In any or all of the above embodiments, the alloy further comprises oneor more grain refiners.

In any or all of the above embodiments, the one or more grain refinersincludes a TiBor master alloy, titanium boride, titanium carbide, or acombination thereof.

In any or all of the above embodiments, the alloy has a total tensileductility of greater than 5%.

In any or all of the above embodiments, the alloy comprises 7.35 wt %copper, 0.14 wt % manganese, 0.4 wt % zirconium, less than 0.1 wt %silicon, minor impurities, and a balance of aluminum.

In any or all of the above embodiments, a component is fabricated fromthe alloy of claim 1.

In any or all of the above embodiments, the component is an enginecomponent.

Also disclosed herein are embodiments of a method for making an alloy,comprising: combining 7 wt % to 10 wt % copper; greater than 0.3 to 0.5wt % zirconium; 0.05 wt % to 1 wt % manganese; greater than 0 wt % to0.1 wt % silicon; and aluminum to form a composition; melting thecomposition; and solidifying the composition to form an alloy.

In some embodiments, the solidification is accomplished by sand casting,die casting, investment casting, or pressure-assisted die casting.

In any or all of the above embodiments, the method further comprisesadding one or more grain refiners to the composition.

In any or all of the above embodiments, the zirconium is present in anamount ranging from greater than 0.3 wt % to less than 0.45 wt %

In any or all of the above embodiments, the method further comprisingpouring the alloy into a mold no more than 5 minutes after the one ormore grain refiners have been added to the composition.

VII. Working Examples Comparative Example

Microstructural Analysis of Low-Zr ACMZ Alloys—In this example, ACMZalloy samples from ACMZ alloys having zirconium content lower than 0.25wt % were prepared and analyzed for comparison purposes. Samples wereprepared were analyzed using a SEM, and micrographs were prepared of theanalyzed samples.

FIG. 1A shows a scanning electron microscope (“SEM”) micrograph of anACMZ alloy sample having a copper content of 6.6 wt. %, with matrixgrains (dark grey) and aluminum-copper intermetallic phases (bright)disposed along the grain boundaries. FIG. 1B shows a SEM micrograph ofan ACMZ alloy sample having a copper content of 8.0 wt %, with matrixgrains (darker grey) and aluminum-copper intermetallic phases (lightergrey) disposed along the grain boundaries. At elevated copper levels, acorrespondingly greater quantity of the aluminum-copper intermetallic isformed. In the sample of the ACMZ alloy having 6.6 wt % copper, theintermetallic phase forms isolated particles at the grain boundaries ofthe matrix phase. In the sample of the ACMZ alloy with 8.0 wt % copper,by contrast, there is sufficient total volume fraction of thealuminum-copper intermetallic for the intermetallic phase to form aninterconnected network along the grain boundaries of the matrix phase.

Without being limited to any particular theory, it is currently believedthat the formation of long, thin, interconnected bands of thealuminum-copper intermetallic at the grain boundaries of ACMZ alloysprovide stress concentrators, as well as a pathway for brittle crackfailure under tensile stress. This, in turn, is believed to embrittlethese alloys, particularly at low temperature or room temperature. Assuch, ACMZ alloys with zirconium content below 0.25 wt % typically donot comprise high copper levels without severe loss of room temperatureductility.

Example 1

Energy Dispersive X-ray Spectroscopy—In this example, ACMZ alloysdesignated “ACMZ 2” and “ACMZ 5,” having compositions listed in Table 1were analyzed SEM Energy Dispersive X-ray Spectroscopy (“EDS”).Specimens for EDS analysis were prepared following standardmetallographic procedures.

TABLE 1 Bulk Alloy Measured Compositions. All values given in wt %.Alloy Cu Mn Zr Fe Si Al ACMZ 2 7.5 0.13 0.09 0.08 0.04 Bal. ACMZ 5 7.40.14 0.35 0.09 0.04 Bal.

For both alloys designated in Table 1, five measurements were taken ofboth the matrix grain composition and the Al—Cu intermetalliccomposition in weight percent, as shown in Table 2.

TABLE 2 Compositional Measurements for Matrix and Intermetallic Phasesin Select Alloys. All values given in wt %. Sample Location Al Mn Cu ZrFe ACMZ 2 Matrix 1 92.64 0.55 6.81 — — ACMZ 2 Matrix 2 90.91 0.48 8.61 —— ACMZ 2 Matrix 3 90.91 0.42 8.66 — — ACMZ 2 Matrix 4 91.04 0.51 8.45 —— ACMZ 2 Matrix 5 90.86 0.45 8.68 — — ACMZ 2 Intermetallic 1 80.97 0.5518.48 — — ACMZ 2 Intermetallic 2 79.41 0.36 20.23 — — ACMZ 2Intermetallic 3 80.71 0.41 18.88 — — ACMZ 2 Intermetallic 4 79.43 0.3720.21 — — ACMZ 2 Intermetallic 5 78.87 0.33 20.8 — — ACMZ 5 Matrix 192.99 0.26 5.87 0.88 0 ACMZ 5 Matrix 2 92.98 0.4 5.91 0.71 0 ACMZ 5Matrix 3 86.32 1.28 10.16 0.94 1.29 ACMZ 5 Matrix 4 93.29 0.28 5.74 0.70 ACMZ 5 Matrix 5 93.79 0.18 5.63 0.4 0 ACMZ 5 Intermetallic 1 77.37 0.222.19 0.23 — ACMZ 5 Intermetallic 2 58.95 0.2 40.32 0.53 — ACMZ 5Intermetallic 3 86.78 0.2 12.57 0.39 — ACMZ 5 Intermetallic 4 69.78 0.230.24 0.18 — ACMZ 5 Intermetallic 5 63.82 0.21 35.91 0 —

From the results in Table 2, an average value for the compositions, inweight percent, of the matrix and Al—Cu intermetallic phases wascalculated and is presented in Table 3 and in FIG. 2.

TABLE 3 Composition Values for Matrix and Intermetallic Phases in SelectAlloys. All values given in wt %. Sample Al Mn Cu Zr Fe ACMZ2 Matrix91.3 0.5 8.2 — — ACMZ2 Particle 79.9 0.4 19.7 — — ACMZ5 Matrix 91.9 0.56.7 0.7 0.3 ACMZ5 Particle 71.3 0.2 28.2 0.3 —

Example 2

SEM Microscopy of ACMZ Alloys—In this example, ACMZ alloys, havingcompositions listed in Table 4, were analyzed using a SEM andmicrographs were prepared of the analyzed samples.

TABLE 4 Composition Values in Select Alloys. All values given in wt %.Alloy Cu Mn Zr Fe Si Al 16HT-2 7.5 0.45 0.23 — 0.05 Bal. ACMZ 5 7.4 0.140.35 0.09 0.04 Bal.

FIGS. 3A and 3B show backscatter electron (BSE) micrographs of themicrostructure of an ACMZ alloy with a composition comprising 7.5 wt %copper, 0.45 wt % manganese, 0.23 wt % zirconium, 0.05 wt % silicon, anda balance of aluminum. The matrix phase is shown as the larger, darkregions. The aluminum-copper intermetallic phase is shown as brighterparticles dispersed along the boundaries between the grains of thematrix phase, as well as in the bulk volume of the matrix phase grains.FIG. 3A shows the majority of the aluminum-copper intermetallic phase inbands corresponding to the grain boundaries between the matrix grains ofthe ACMZ alloy. FIG. 3B is a higher magnification image that clearlyshows the boundaries between the matrix grains of the ACMZ alloy.

FIGS. 4A and 4B show micrographs of the microstructure of an ACMZ alloyaccording to the present disclosure with a composition comprising 7.4 wt% copper, 0.154 wt % manganese, 0.35 wt % zirconium, 0.04 wt % silicon,iron below 0.1 wt %, and a balance of aluminum. FIG. 4A shows a lowmagnification view of the alloy, exhibiting a roughly uniformdistribution of equiaxed grains. FIG. 4B shows a high magnification viewof the microstructure with the matrix phase shown as the larger, darkregions and the aluminum-copper intermetallic phase shown as brighter,rounded particles. As shown in FIG. 4B, the intermetallic phase isdispersed along the boundaries between the grains of the matrix phase,as well as in the bulk volume of the matrix phase grains. When comparedwith the ACMZ alloy shown in FIGS. 3A and 3B, the alloy shown in FIGS.4A and 4B demonstrates rounded and well-dispersed intermetallic phaseparticles.

Example 3

Mechanical Behavior of ACMZ Alloys—In this example, the tensileproperties of samples of ACMZ alloys according to the embodimentsherein, having zirconium contents from 0 wt % to 0.35 wt % and coppercontents from 7.3 wt % to 8.0 wt % were measured. Samples were preparedhaving a geometry in compliance with the ASTM E8 standard for thetensile testing of metallic materials. Samples were tested to tensilefailure, and the total elongation at failure, yield strength (“YS”), andultimate tensile strength (“UTS”) of each sample was measured.

The results of the mechanical testing are summarized in FIG. 5. Theresults of this tensile testing demonstrate a trend of increased totalelongation at failure with increasing zirconium content. Without beinglimited to a particular theory, it is currently believed that that thepresence of zirconium in the alloys modifies the interfacial surfaceenergy between the matrix phase and the aluminum-copper intermetallicphase. This is believed to cause the intermetallic phase to take on amore rounded morphology, and in some cases to become partially dispersedwithin the bulk volume of the matrix grains, rather than solely at thegrain boundaries. A more rounded morphology may provide reduced stressconcentration at the interface between the intermetallic and matrixphases. A partial dispersion of the intermetallic phase within the bulkvolume of the matrix grains may correspondingly reduce the fraction ofthe intermetallic phase formed along the grain boundaries, furthermitigating the embrittling effect of the intermetallic.

To isolate the effect of increasing Zr content, additional testing wasconducted on ACMZ alloys with nominal compositions ofAl-7.5Cu-xZr-0.15Mn-0.05Si, where the numbers indicate wt % of eachelement, x indicates the wt % zirconium, which ranged from 0-0.4 wt %.Samples were prepared having a geometry in compliance with the ASTM E8standard for the tensile testing of metallic materials. As-measuredcompositions of the tested alloys are presented in Table 5.

TABLE 5 Measured Compositions of ACMZ Alloys. All values given in wt %.Nominal Zr Content Cu Mn Zr Fe Si Al 0    7.69 0.14 <0.01  0.08 0.03Balance 0.1 7.5 0.13 0.09 0.08 0.04 Balance 0.4  7.35 0.14 0.35 0.090.04 Balance

The results of this mechanical testing are summarized in FIG. 6. FIG. 6demonstrates a marked improvement in the mechanical behavior of thealloy at elevated levels of zirconium. In particular, total tensileelongation at failure improves from 1% to 2% at measured zirconiumlevels below 0.1 wt % and from 1% to approximately 5% at a measuredzirconium content of 0.35 wt %.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

We claim:
 1. An alloy comprising: 7 wt % to 10 wt % copper; greater than0.3 wt % to 0.5 wt % zirconium; 0.05 wt % to 1 wt % manganese; greaterthan 0 wt % to 0.1 wt % silicon; and aluminum.
 2. The alloy of claim 1,wherein the alloy is a cast alloy and has a microstructure comprising analuminum matrix phase and an intermetallic phase comprising copper andaluminum.
 3. The alloy of claim 2, wherein the intermetallic phase has arounded geometry.
 4. The alloy of claim 2, wherein the intermetallicphase further comprises zirconium.
 5. The alloy of claim 2, wherein thealuminum matrix phase further comprises a plurality of grain boundariesbetween aluminum matrix grains and the intermetallic phase is partiallydistributed along the plurality of grain boundaries and partiallydistributed within the volume of the aluminum matrix grains.
 6. Thealloy of claim 1, wherein the alloy further comprises one or moreelements selected from nickel, cobalt, titanium, boron, iron, magnesium,or antimony.
 7. The alloy of claim 6, wherein the titanium is present inthe alloy in an amount ranging from greater than 0.0 wt % to 0.3 wt %and the boron is present in the alloy in an amount ranging from greaterthan 0 wt % to less than 0.07 wt %.
 8. The alloy of claim 1, wherein thealloy comprises 7.5 wt % copper, greater than 0.3 wt % to 0.4 wt %zirconium, 0.15 wt % Mn, less than 0.05 wt % silicon, and a balance ofaluminum.
 9. The alloy of claim 1, wherein the alloy comprises greaterthan 0.3 wt % zirconium to less than 0.5 wt % zirconium.
 10. The alloyof claim 1, wherein the alloy further comprises one or more grainrefiners.
 11. The alloy of claim 10, wherein the one or more grainrefiners includes a TiBor master alloy, titanium boride, titaniumcarbide, or a combination thereof.
 12. The alloy of claim 1, wherein thealloy has a total tensile ductility of greater than 5%.
 13. The alloy ofclaim 1, wherein the alloy comprises 7.35 wt % copper, 0.14 wt %manganese, 0.4 wt % zirconium, less than 0.1 wt % silicon, minorimpurities, and a balance of aluminum.
 14. A component fabricated fromthe alloy of claim
 1. 15. The component of claim 14, wherein thecomponent is an engine component.
 16. A method for making an alloy,comprising: combining 7 wt % to 10 wt % copper; greater than 0.3 wt % to0.5 wt % zirconium; 0.05 wt % to 1 wt % manganese; greater than 0 wt %to 0.1 wt % silicon; and aluminum to form a composition; melting thecomposition; and solidifying the composition to form the alloy.
 17. Themethod of claim 16, wherein solidifying the composition to form thealloy is accomplished by sand casting, die casting, investment casting,or pressure-assisted die casting.
 18. The method of claim 16, whereinthe method further comprises adding one or more grain refiners to thecomposition.
 19. The method of claim 16, wherein the zirconium ispresent in an amount ranging from greater than 0.3 wt % to less than0.45 wt %
 20. The method of claim 18, wherein the method furthercomprising pouring the alloy into a mold no more than 5 minutes afterthe one or more grain refiners have been added to the composition.